In plain words
Nature is subject to change — but is the Ātma subject to change too? Nature, and all its various forms, are constantly changing; it keeps taking on one form after another. The Ātma, however, undergoes no such changes; it cannot undergo them. Evil deeds contract it — that is to say, evil deeds are precisely those that narrow down the Ātma's own inherent Jñāna of truth and its purity. Deeds that instead bring the Ātma's own innate radiant glory into visible form are called good deeds. The Ātma was originally pure; but afterward it came to be contracted. Through the performance of good deeds, it expands once more and regains its innate purity. This opportunity exists equally for all people; in time's own ripening, liberation comes to everyone — yet this universe itself never comes to an end. It is eternal. This is the second doctrine. The first doctrine's name is Dvaita. According to this second doctrine, God, the Ātma, and Nature are three distinct entities. But since Nature is entirely God's own body, and since the Ātma is itself precisely the jīva, these three come together and are, in truth, a single entity — a higher stage in the unfolding of spiritual inquiry.
This doctrine is called Viśiṣṭādvaita. According to the dualist doctrine, this universe is like some great machine that God has set in motion. According to Viśiṣṭādvaita, it is instead a single organized structure, densely pervaded within by God's own Ātma. Then come the followers of the final doctrine, the Advaitins. In their view, God alone is both the material and the efficient cause of this universe — and therefore God alone has become the very form of the whole universe. Everyone must accept this; there is no escaping it. This is the supreme truth. The Advaitins point out that to say 'God is the Ātma' and 'the universe is His body,' while also saying 'this body is subject to change but the Ātma alone is unchanging,' is meaningless: if it were correct, what purpose would be served at all in calling God the material cause of this universe?